A distraught dog-owner said she was heartbroken after she watching her pet get "ripped apart like a rag doll" by another dog.
Dasha Darazhio was with her three-year-old son when their six-year-old Yorkshire terrier Bru was attacked by a Staffordshire terrier.
They were enjoying lunch with friends at the Waggon and Horses pub in Watling Street on Friday when the attack took place. Bru was taken straight to the vets but died on Saturday morning.
Miss Darazhio said she has been left "heartbroken" because Bru was "like a child" to her.
She said: "We were sitting in the sunshine, when we saw a couple walk in with three Staffordshire terriers.
"The dogs were very aggressive so I put my little dog on a lead and tied it around the bench.
"Suddenly one of their dogs broke its lead and ran over and killed my dog.
"This happened right by my feet, in front of my son and me. It happened so quickly."
Miss Darazhio tried to save Bru and after about 20 seconds she was able to punch the attacking dog on the nose.
The 30-year-old continued: "It was too late. My tiny little sweet Yorkie had all her insides ripped out."
"The pain I feel every second when I am awake is not describable. I was so close to my dog and she was the kindest sweetest thing ever.
"She wouldn't hurt a fly. I will never get the picture of what happened out of my head.
"Every time my son Max asks me when Bru is coming home it breaks my heart.
"What makes it worse is the way Bru died and the fact I didn’t get to say goodbye. To be mauled to death is absolutely traumatic."
The two owners of the Staffordshire terrier tried to call it off, but later left the scene.
Bru and Miss Darazhio's son Max
The pub's assistant manager Lou Chapman was working when the incident happened.
He said: "The attack was absolutely awful. It was all very quick and sudden, and certainly has never happened here before.
"We have never seen the owners before, but their dog was massive. They need to be found as the dog is dangerous."
Miss Darazhio reported the incident to the police, who are trying to trace the owners.
She continued: "I have been left heartbroken, and now the dog has a taste for blood I worry that it is only a matter of time before something similar happens again. I just wish I had put Bru on my lap and off the floor."
The owners are described as a white woman with very long blonde hair, aged between 25 and 30, and a man, aged between 25 and 30, with dark hair which was long on top with shaved sides.
Investigating officer from Hertfordshire Police, PC Phil Tuck, said: "The owner is distraught about the loss of her beloved pet and we are doing everything we can to trace the dog owners, with support from colleagues at Hertsmere Borough Council.
"Fortunately incidents like this are very rare."
Anyone with information is asked to contact Hertfordshire Constabulary’s non-emergency number 101.